265/40/17 or 255/40/17 on 8.5" wheel?

[325i Vert]

What is the widest tire you would go on a 8.5? I did a search but didnt come back with anything that answered my question. I know 245's are good for the 8.5 but was not sure if the 265 or 255 series would be okay as well. Are these sizes too wide for that size rim? Thanks!

Josh K

[SleepRM3]

Most say that 255/40-17 is the widest you can go on 8.5 wides. I know of some who squeezed 275/40-17 Kumhos on 8.5 wides. Problem with this is the width of the tire doesn't get used well b/c the tire's being squeezed by the relativley narrow rim width. 265s are happiest with 9.5- or 10-inch wide rims.

Frankly 245/40-17s are happiest on 9-wides, and that 8.5 is very slightly narrow for that size--but then again, I like the slightly stretched tire look on my wheel rims.

Look up measuring rim widths for 235/40-17 tires--invariably, the tire maker uses 8.5-wide rims as their "spec" rim width.

The general rule for rim and tire widths is 90%. The rim width should be at least 90% of the tire's section width. For instance, your 255/40-17 is 10 inches wide in section width. Thus the minimum rim width for a 255/40-17 is 9 wide--and in fact if you look up the "spec" rim width for 255s, they're usually 9 wides.

[Young Version]

My car's spare has a 245/40(an old Continental) on a 7.5 inch wheel, but the actual tire width is nowhere near that of the 245/45 Azenis RT615 I've got. Judging by this example, it really depends on the tire. However, I believe that a 255 would easily fit on an 8.5 inch wheel.

[carcrazed4life]

255/40/17 on 17x8.5

[KimoSabe]

So it should not be a problem running 235/45/17 on 7.5s in the front with 255/40/17 on 8.5s in the rear?? Will it require any fender rolling. TIA

[KarlSpackler]

all Depends On Offset

[KimoSabe]

all Depends On Offset

On stock staggered DSIIs. 41et?? I did say I was a newbie...TIA

[SleepRM3]

235/45-17 is too tall for the front. Stick with 225/45-17.

Why are you upsizing the tires on the stock rims? The extra tire section width isn't going to result in added traction--your rims are not any wider, and limit the ultimate section width. General rule is tire section width increases 0.2 inches with every 0.5-inch increase in rimwidth.

You're just adding more weight, cost, and the probability of rubbing problems.

[Darwin006]

255 is the most

[uansari1]

235/45-17 is too tall for the front. Stick with 225/45-17.

Why are you upsizing the tires on the stock rims? The extra tire section width isn't going to result in added traction--your rims are not any wider, and limit the ultimate section width. General rule is tire section width increases 0.2 inches with every 0.5-inch increase in rimwidth.

You're just adding more weight, cost, and the probability of rubbing problems.

Interestingly, I was thinking of the same thing when I looked at Kumho MX's on Tirerack. If I went with 235/45 F and 255/40 R, it would actually be cheaper than the OEM sizes. For some reason the 225/45's are about $10 more than the 235's...

Anyone know if this would be an issue with the stock suspension on DS2's?

Either way, it seems like upsizing may not aid traction considerably, so maybe I'll go with the OEM sizes. I initially just wanted to upsize in the front to even out the handling a bit. Problem is Kumho doesn't make 235/40 MX's. :(